Rotary tank cleaning spray nozzle assemblies require complex multi-directional drives for rotating the spray nozzles in a manner that ensures the discharging spray covers all areas of the tank. Such spray nozzle assemblies require numerous parts which can be cumbersome to assemble and disassemble for sanitary cleaning as required after each usage. Threaded components of the nozzle assembly can be particularly cumbersome to assemble and disassemble, and the threads of such connections must be reliably sealed from the processing fluids. Leakage of seals can cause contamination and bacteria to accumulate within the threads which can be difficult to clean to sanitary standards.
Such spray nozzle assemblies commonly have a vertically oriented stationary housing having a liquid inlet at an upper end, a rotary housing supported at a lower end for relative rotation about a central axis of the stationary housing, and a nozzle carrying hub supported radially outwardly of the rotary housing for rotation about an axis transverse to the axis of the stationary housing. The nozzle carrying hub typically is rotatably driven by bevel gearing between the stationary housing and the nozzle carrying hub which due to their angular interaction can be difficult to machine, service, and clean.
With the nozzle carrying hub acting as a radial extension of the rotary housing of such spray nozzle assemblies, during rotation of the rotary housing, load carrying bearings can incur relatively high stresses. This can cause wear, maintenance, failure, and costly replacement of bearings.